Ethylene and propylene, or light olefins, are important for the production of commercially important plastics, namely polyethylene and polypropylene. Other important polymer precursors include vinyl chloride, ethylbenzene, ethylene oxide and other compounds, which are derived from the light olefins. The production of light olefins is primarily produced through the cracking of heavier hydrocarbons from hydrocarbon feedstocks derived from petroleum.
A light olefin plant is a combination of reactors and gas recovery systems. The reactors include cracking units for generating a stream having light olefins and fractionation units for separating the light olefins from the other hydrocarbon components in the product streams from the reactors.
The increasing demand for light olefins has led to the search for other sources as the cost of petroleum has increased. Among the new sources include oxygenates that can be derived from biomass, and other sources. Common oxygenates include alcohols and in particular methanol. In particular, natural gas comprising primarily methane can be converted to methanol, and the methanol can be converted to light olefins. The oxygenates are converted through a reaction process to generate a product stream comprising light olefins.
One conversion process is generally referred to as methanol to olefins (MTO) process, and the process involves a catalytic reaction and is carried out in a catalytic reactor to generate a product stream of light olefins. The catalyst for the conversion of oxygenates to olefins include solid catalyst such as zeolites. Zeolites used in the MTO process are described in numbers patents. A process for preparing zeolites is described in U.S. Pat. No. 3,957,689. A process for making an improved attrition resistant catalyst is described in U.S. Pat. No. 4,987,110. A process for producing hardened microspheres is described in U.S. Pat. No. 5,352,645. Numerous other patents describe the making of better catalyst for improved reactions, and for improved hardness of the catalyst particles.
Catalysts having improved attrition resistance is important because the reactor environment is a severe physical environment. The MTO reactor is generally a fluidized bed and the catalyst particles are subject to constant contact and rubbing against other catalyst particles and with physical equipment where the catalyst particles are transferred through, or stirred within.
Improving the system for the production of light olefins can increase the catalyst life and improve the process to make the production more economical.